将base64字符串转换为图像

Question

我正在尝试使用 jquery 插件裁剪/调整用户个人资料图像的大小，即crop.js，它通过 ajax 将用户图像作为 base64 发送到我的控制器作为

$.ajax({
         type: "post",
         dataType: "json",
         url: "${g.createLink(controller: 'personalDetail', action:'uploadUserImage')}",
         data: { avatar: canvas.toDataURL() }

        });

但我无法解码这个 base64

'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAPAAAADwCAYAAAA+VemSAAAgAEl...==' 

string as Image,你们能指导我如何将我的base64字符串作为图像保存在我的服务器上吗？

Answer 1

在服务器中，执行如下操作：

假设

String data = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAPAAAADwCAYAAAA+VemSAAAgAEl...=='

然后：

String base64Image = data.split(",")[1];
byte[] imageBytes = javax.xml.bind.DatatypeConverter.parseBase64Binary(base64Image);

然后你可以对字节做任何你喜欢的事情，比如：

BufferedImage img = ImageIO.read(new ByteArrayInputStream(imageBytes));

Answer 2

这假设了一些事情，即您知道输出文件名是什么，并且您的数据以字符串的形式出现。我相信您可以修改以下内容以满足您的需求：

// Needed Imports
import java.io.ByteArrayInputStream;
import sun.misc.BASE64Decoder;


def sourceData = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAPAAAADwCAYAAAA+VemSAAAgAEl...==';

// tokenize the data
def parts = sourceData.tokenize(",");
def imageString = parts[1];

// create a buffered image
BufferedImage image = null;
byte[] imageByte;

BASE64Decoder decoder = new BASE64Decoder();
imageByte = decoder.decodeBuffer(imageString);
ByteArrayInputStream bis = new ByteArrayInputStream(imageByte);
image = ImageIO.read(bis);
bis.close();

// write the image to a file
File outputfile = new File("image.png");
ImageIO.write(image, "png", outputfile);

请注意，这只是所涉及部分的一个示例。我根本没有优化这段代码，它已经写在我的脑海里了。

Answer 3

ImageIO.write() 默认会压缩图像 - 压缩后的图像尺寸较小但有时看起来很奇怪。我使用BufferedOutputStream 保存字节数组数据 - 这将保持原始图像大小。

代码如下：

import javax.xml.bind.DatatypeConverter;
import java.io.*;

public class ImageTest {
    public static void main(String[] args) {
        String base64String = "data:image/jpeg;base64,iVBORw0KGgoAAAANSUhEUgAAAHkAAAB5C...";
        String[] strings = base64String.split(",");
        String extension;
        switch (strings[0]) {//check image's extension
            case "data:image/jpeg;base64":
                extension = "jpeg";
                break;
            case "data:image/png;base64":
                extension = "png";
                break;
            default://should write cases for more images types
                extension = "jpg";
                break;
        }
        //convert base64 string to binary data
        byte[] data = DatatypeConverter.parseBase64Binary(strings[1]);
        String path = "C:\\Users\\Ene\\Desktop\\test_image." + extension;
        File file = new File(path);
        try (OutputStream outputStream = new BufferedOutputStream(new FileOutputStream(file))) {
            outputStream.write(data);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Answer 4

简单是：

import java.util.Base64;

解码：

byte[] image = Base64.getDecoder().decode(base64string);

编码：

String text = Base64.getEncoder().encodeToString(imageData);

Answer 5

服务器端将文件/图像编码为 base64String 以供客户端使用

public Optional<String> InputStreamToBase64(Optional<InputStream> inputStream) throws IOException{
    if (inputStream.isPresent()) {
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        FileCopyUtils.copy(inputStream.get(), output);
        //TODO retrieve content type from file, & replace png below with it
        return Optional.ofNullable("data:image/png;base64," + DatatypeConverter.printBase64Binary(output.toByteArray()));
    }

    return Optional.empty();
}

服务器端 base64 图像/文件解码器

public Optional<InputStream> Base64InputStream(Optional<String> base64String)throws IOException {
    if (base64String.isPresent()) {
        return Optional.ofNullable(new ByteArrayInputStream(DatatypeConverter.parseBase64Binary(base64String.get())));
    }

    return Optional.empty();
}

Answer 6

  public Optional<String> InputStreamToBase64(Optional<InputStream> inputStream) throws IOException{
    if (inputStream.isPresent()) {
        ByteArrayOutputStream outpString base64Image = data.split(",")[1];
byte[] imageBytes = javax.xml.bind.DatatypeConverter.parseBase64Binary(base64Image);

然后你可以对字节做任何你喜欢的事情，比如：

BufferedImage img = ImageIO.read(new ByteArrayInputStream(imageBytes));ut = new ByteArrayOutputStream();
        FileCopyUtils.copy(inputStream.get(), output);
        //TODO retrieve content type from file, & replace png below with it
        return Optional.ofNullable("data:image/png;base64," + DatatypeConverter.printBase64Binary(output.toByteArray()));
    }

    return Optional.empty();

Answer 7

嗨，这是我的解决方案

Javascript代码

var base64before = document.querySelector('img').src;
var base64 = base64before.replace(/^data:image\/(png|jpg);base64,/, "");
var httpPost = new XMLHttpRequest();
var path = "your url";
var data = JSON.stringify(base64);

httpPost.open("POST", path, false);
// Set the content type of the request to json since that's what's being sent
httpPost.setRequestHeader('Content-Type', 'application/json');
httpPost.send(data);

这是我的 Java 代码。

public void saveImage(InputStream imageStream){
InputStream inStream = imageStream;

try {
    String dataString = convertStreamToString(inStream);

    byte[] imageBytes = javax.xml.bind.DatatypeConverter.parseBase64Binary(dataString);
    BufferedImage image = ImageIO.read(new ByteArrayInputStream(imageBytes));
    // write the image to a file
    File outputfile = new File("/Users/paul/Desktop/testkey/myImage.png");
    ImageIO.write(image, "png", outputfile);

    }catch(Exception e) {
        System.out.println(e.getStackTrace());
    }
}


static String convertStreamToString(java.io.InputStream is) {
    java.util.Scanner s = new java.util.Scanner(is).useDelimiter("\\A");
    return s.hasNext() ? s.next() : "";
}

Answer 8

这是 Ayano 的出色答案，但在 Clojure 中：

(:import (java.awt.image BufferedImage)
         (javax.xml.bind DatatypeConverter)
         (java.io File BufferedOutputStream FileOutputStream))

(defn write-svg-encountered-image [svg-img-data base-filename]
  (let [[meta img-data] (str/split svg-img-data #",")
        extension (case meta
                    "data:image/jpeg;base64" ".jpeg"
                    "data:image/png;base64" ".png"
                    (throw (Error. (format "Unrecognised image metadata in SVG:" meta))))
        path (str base-filename extension)
        file (File. path)
        data-bytes (DatatypeConverter/parseBase64Binary img-data)
        os (BufferedOutputStream. (FileOutputStream. file))]
      (.write os data-bytes)))